In the current environment, being Secretary of Pennsylvania's Department of Environmental Protection is probably one of the hardest jobs in state government.

There are energy policy wars going on that pit one of the major drivers of the state and national economies - copious natural gas deposits - squarely against unyielding scientific issues that those same economic drivers contribute to.

Then, there is a divided government in Pennsylvania that often finds the Democratic governor and the Republican-controlled legislature starting from opposing corners on many of those issues.

In that context, some said Friday, former Secretary of Environmental Protection John Quigley - who resigned his $152,657-a-year cabinet post after a brief meeting with Gov. Tom Wolf Friday - probably never had a chance.

He was, one observer concluded, probably too green in an environment where people live in shades of gray.

To some, this showed most starkly in the consideration this winter and spring of new regulations to govern the resurgent oil and gas drilling industries - a powerful force in state politics.

Legislators, mostly Republican but some Democrats too, sought to soften the new rules as they wended through the rule-making process, and at times they thought they had Quigley's buy-in.

He acted, said Sen. John Yudichak, a Luzerne County Democrat from anthracite coal country, like a political advocate instead of the leader of a state agency charged with finding balance in energy policy.

"Quigley was simply off the reservation, and the governor recognized that," Yudichak said Friday night as word of Quigley's resignation spread. "He wasn't able to build relationships in the General Assembly... and I applaud the governor for making a quick decision to move forward."

"There was a lot of frustration that he would say one thing (in meetings with lawmakers) and then ultimately do what he wanted to do," said Drew Crompton, chief of staff to Senate President Pro Tempore Joe Scarnati, R-Jefferson County.

"A secretary has that right... but I think at some point it causes the frustration to boil over."

Quigley, a 56-year-old former mayor of Hazleton, is not without his supporters.

Rep. Greg Vitali, a leading voice for green causes in the General Assembly from Delaware County, hailed Quigley as a warrior with the spine to stand up to energy companies that, in his view, have had it too good for too long in Pennsylvania.

"The polluters this evening are I am sure overjoyed," Vitali said, "because John was a very strong advocate for the enforcement of environmental laws and regulations, and protecting public health and the environment."

The new drilling regulations, supporters say, would mark a critical step in helping Pennsylvania avoid a fresh round of environmental scarring like that sustained from the coal mining boom 100 years ago.

But now, Quigley's abrupt departure means the Wolf administration, in its first year-and-a-half, has lost - for different reasons - three strong, pro-environment voices in Quigley, former Policy Secretary John Hanger and former chief of staff Katie McGinty.

(Both McGinty and Hanger served as DEP secretaries under former Gov. Ed Rendell.)

With Quigley gone, Vitali said, the administration "is stripped of high-level personnel who have both a thorough understanding of environmental issue and a deep commitment to them."

Administration officials could not immediately be reached for comment on Vitali's remarks.

But one source close to Wolf who asked not be identified in order to speak about internal discussions said Friday there were strained relationships even within the administration that caused Wolf to re-evaluate Quigley's standing.

The "straw that broke the camel's back," this source said, was an April e-mail Quigley authored after several Democratic state senators broke with the administration on a greenhouse gas emission bill.

The email - in which Quigley expressed his frustration at delays on that issue and the new drilling rules, and exhorted environmental advocacy groups to fight harder for their causes - was quickly followed by issue advertisements criticizing Yudichak and Sen. John Blake for their votes.

The senators quizzed Wolf's senior staff about a possible connection. Groups who ran the ads have since denied being directed by Quigley to run them.

But at a time when Wolf is said to be eyeing the drilling regulations as a place to build good faith with legislative Republicans before the upcoming 2016-17 budget talks, the source said, the email kerfuffle gave Wolf and his senior staff fresh reason to evaluate whether Quigley was hurting more than helping, the source said.

The governor's conclusion became self-evident Friday. Wolf tapped Patrick McDonnell, who had been DEP's policy director, as acting secretary.

With potential fights over the new drilling rules still looming, Crompton said lawmakers will be looking to see if with new leadership and tone at DEP they can "sand the edges" of the new rules.

Quigley, meanwhile, refused Friday night to respond to a PennLive reporter who stopped at his Camp Hill home.